Carburetor



July 21, 195 3 E. G. BAREHAM EI'AL 2,646,265

, v CARBURETOR Filed Jan. 50, 1950 2 Sheets-Sheet 1 a .FIG.I. n l

' INVENTORS ERIC 6. BARE/M M WILL/AH LAYL AND ATTORNEY Patented July 21,1953 I liam Layland, Kings Heath, Birmingham, England, assignors-to TheAustin Motor Company Limited, Birmingham, England Application January30, 1950, Serial No. 141,212

In Great Britain February 21, 1949 The invention relates to carburetorsof the constant suction type, that isto say that in which thechoke iscontrolled by a piston'working in acylinder and exposed 'at' one side toatmospheric pressure and at the other side exposed to the suction in themixing chamber of the'carburetor, the'arangement being such that, as thethrottle is opened the piston moves in'a direction to increase theairinlet to the carburetor so 1 that the'suction in the mixing chamberremains substantially constant. Attached to the piston is a taperedneedle valve entered into a jet tube,

the arrangement being such that,'as the piston moves-in a direction toincrease the air inlet to the carburetor, the needle valve moves to. in-

crease the fuel supply.

I In order to provide a rich mixture to facilitate cold starting, meansareprovided for moving the 3 Claims. (Cl. 26 151) ment or the actuatingleverin the opposite direction takes place first about the secondfulcrum so asto move thejet tube and throttle operatinglever'simultaneously, to reduce the throttle openingand fu'el supplyproportionately until the jet tube is restored to normal position andthe actuating lever is disengaged from the supporting abutment, and thenabout the fulcrum on the jet tube so as to move'the throttle to its jettube in a direction away fromthe piston temporarily to increase the afuel, supply.

It is also desirable to provide means for opening'the main throttlevalvelto a small extent during, and also for a shortperiod after,starting; thus securing .a faster idling speed than normal. Therefore,

the means for moving the jet tube have been coupled to the throttlelever 'sothat moving the jet tube to increase the fuel supply alsoincreases the throttle opening to a small extent," This simplearrangement; has the disadvantage that it causes an over-rich mixturewhen the engine is fast idling after being startedup. To overcome this,,meanshave been provided whereby the throttle is opened to a slightextent beyond normal idlin position before the jet tube is moved toincrease the fuel supply, and the pres j ent invention has for itsobjectto provide sim' ple and improved means for this purpose. Ina-carb-uretor of the type referred to and according to the invention,the means for moving the jet tube comprises a spring-loaded actuatinglever fulcrumed. on the jet tube'and connected by a link toathrottle-operating lever, and said actuating lever has a lost motionconnection with a second fulcrum, which is fixed, and it is adapted tobe engaged, at times; with ayfixed supporting abutment. The arrangementis, such k that movement of the actuating lever in one direction takesplace'firstabout its fulcrum with I the jet tube, to eiiectpartialopening ofthe throttle without moving the jet'tube, and then about the,second fulcrum to move the jet tube and the throttle-operating leversimultaneously, so :as to increase thelfuel supply and throttle openingand engage the actuating lever With..the p rt ng abutment, whilstsubsequent-movenormal or slow idlin g position.

Thusafter starting upthe engine, the throttle opening and fuel supplycan be reduced propor.-' tionately until the jet tube isin' its normalosition. and the throttle is still partially open to give fast idlingwithout an unduly rich mixture. When the'enginehas warmed upsuificiently under these conditions, furthermovement of the saidactuating lever, about the fulcrum on the jet tube and permitted by thelost motion connectionof the actuating'lever with the second fulcrum,returns the thro ttle'to its normal position togive ordinary runningconditions.

The invention will now be more fully described with reference to theembodiment shown, by way of example, in the accompanying drawings, in

which: v Fig. 1 isan-elevation of the carburetor with the'jet tube andthrottle controls in their normal running positions.

Fig. 2 is a side elevation of Fig. 1.

Fig. 3 is a fragmentary view, similar to Fig. 1, but showing thecontrols in thefast idling position.

. Fig. 4 is a similar fragmentaryview showing the controls in thestarting position; m Fig. 5 is a vertical section through-the carburetorto showthe parts within.

Referring to the drawings and at first mor especially to Figure 5, thecarburetor is of the kind in which a'p'iston 25 works in a cylinder 1.The lower side of the piston is exposed to atmospheric pressurethrough-a vent .26'and at its upper side is 'incommunication with amixing chamber 2'! through av passage 21*, into which chamber the jet 28opens.v The throttle valve 29 is actuated by a throttle lever. 5, seeFigure 2. At.-

tache'd to the under side of the piston 25 is a plunger 30 whichcontrolsthe entry ofair to the mixing chamber 21. Depending from the plunger 30is a tapered needle valve 3! which is entered intothe upper'end of a jettube 2 to which fuel is suppliedfrom afloat chamber 4.

Any tendency for the suction in the mixing chamber 21 torise produces acorrespondingincrease of suction above the piston 25'which 3 causes itto lift and raise the plunger 3!) allowing an increased air fiow intothe mixing chamber 21. Thus the suction in the mixing chamber tends toremain constant at all times. Lifting of the plunger also lifts theneedle valve 3| to increase the fuel supply.

To facilitate starting from cold thejet tube V 2 is arranged to slide ina bore of the carburetor casing. By lowering the tube 2 an increasedfuel supply is obtained from the fioat chamber 4.

The parts so far described are common practice in carburetors of theconstant'suction type.

The means provided for moving down the jet tube 2 comprises a two-armedlever. 8 one arm of which extends downwardly and the other substantiallyhorizontally to the left, as seen in Figs. 1, 3 and 4. The lever 8 isoperated by a Bowden cable 9 secured to the depending arm of said leverand connected to a mixture control knob on the instrument board of thevehicle, the sheath of the cable 9 being clamped in a downwardlyextending arm ll] of a two-part bracket l l which is fixed to thecarburetor body 3. The

horizontal arm of the lever 8 is pivoted'at 12 to the lower end ofrthejet tube 2, whilst, at the junction of its two arms, said lever isformed with a short arcuate slot 13: concentric with the pivot 12 andengaged with a pivot stud i4 fixed in the bracket 1 I. The jet tube 2 isnormally maintained up, against the abutment, by a tension coil spring16 connecting the horizontal arm of the lever 8 to a lug I? on thecarburetor body, the upper end of the slot I3 then being engaged withthe stud M.- Extending upwardly from the junction of the arms of thelever 8 is a hook it the nose of whichispresented to the left andnormally lies close to the right-hand side of the stud l9 fixed in thebracket 1 I Connected to a short lever '28, which is adapted tocooperate wlth an adjustable abutment screw 2| on the throttle lever 1so as to "operate the latter, is a downwardly extendinglinkiz whichis'pivoted at its lower endto a shortspindle'23 mounted to turn in aboss 21!.on the lever B at azshort distance to the right of the slot.

The effect of moving the downward arm .of the lever 8 to the'right, bymeans iof'the'cable 9, is at first to turn said lever about the pivot 12until the lower end of the slot13 engages the fixed pivot stud [4. Thismovement has no effeet on the jet tube 2 but it opens the throttle to asmall extent, by pressing up the 'link"22-, and it also brings the noseof the hook l8 above the level of the fixed stud [9, as shown in Fig."3. Further movement of the lever 8 in the same direction takes placeabout the pivot stud 14, so

that the jet tube 2 is drawn down, against the 7 the parts then being inthe positions shown in Fig. 4.

During the first part of the release of the downward arm of the lever 8,the latter turns about the pivot l4 under the return action of thespring 16, because the lever 8 has its hook i8 still engaged with thestud IS. The effect, therefore, is to reduce the throttle opening and toraise the jet tube 2 to reduce the fuel supply proportionately. When thelever 8 has been released from the position indicated by the centre lineA to that indicated by the centre line B in Fig. 1, that is to say fromthe position shown in Fig. 4 to that shown in Fig. 3, the jet tube 2 hasbeen raised to its normal running position but the throttle is stillpartially open to allow fast idling without an unduly rich mixture, andthe hook I8 is disengaged from the stud it so that further release ofthe lever 8 allows it to turn about the pivot l2, under the action ofthe spring 5, allowing the throttle to close to the normal 'or minimumidling position determined by the adustable abutment screw 6 coming intoengagement with a fixed abutment on the carburetor body 3.

If desired the lower end of the link 22 may be pivoted to the lever 8 maposition beneath the slot l3. This leaves the initial opening of thethrottle the same as above described, but it delays the further openingof the throttle valve,

Whereas the invention has been described with reference to a carburetorwith a vertically disposed cylinder and piston or plunger, it mayequally well be applied to carburetors in which these parts are inclinedto the vertical, or even horizontal.

Having fully described our invention, what we claim and desire to secureby Letters Patent is:

1. In a carburetor of-tlie constant suction type having a movablejet-tube and a throttle operating lever, jet tube operating meanscomprising a spring loaded actuating lever; fulcrumed on the jet tube, alink connected to the actuating lever and engaging the throttleoperating lever, a second fulcrum which is fixed, a lost-motionconnection between said actuating lever and said second fulcrum, a fixedsupporting abutment, and means on said actuating lever adapted to engagesaid supporting abutment during a portion of themovenient of saidactuating lever, whereby movement of the actuating lever in onedirection takes place first about its fulcrum on the jet tube to effectpartial opening of the throttle without moving the jet tube, and thenabout the second fulcrum to move the'jet tube and the throttle operatinglever simultaneously to. increase the fuel supply and throttle openingproportionately and engage said means on the actuating lever with thesupporting abutment, and subsequent movement of the actuating lever inthe opposite direction takes place first about the second fulcrum so asto move the jet tube and throttle operating lever simultaneously toreduce the throttle opening and fuel supply proportionately until thejet tube is restored to normal position and said means on the actuatinglever is disengaged from the supporting abutment, and then about thefulcrum on the jet' tube so as to move the throttle to its normal slowidling position.

2. In a carburetor of the constant suction type having a movable jettube and a throttle operating lever, jet tube operating means comprisinga spring loaded actuating lever fulcrumed on the jet tube, a linkconnected to the actuating lever and engaging the throttle operatinglever, a fixed pivot stud constituting a second fulcrum for saidactuating lever, aslot in said actuating lever engaged With said. fixedpivot stud to afford a lostmotion connection, a fixed supportingabutment, and means on said actuating lever adapted to engage saidsupporting abutment during a portion of the movement of said actuatinglever, whereby movement of the actuating lever in one direction takesplace first about its fulcrum onthe jet tube to effect partial openingof the throttle throttle operating lever simultaneously to in-' creasethe fuel supply and throttle opening proportionately and engage saidmeans on the act-uating lever with the supporting abutment, andsubsequent movement of the actuating lever in the opposite directiontakes place first about the second fulcrum so as to move the jet tubeand throttle operating lever simultaneously to reduce the throttleopening and fuel supply proportionately until the jet tube is restoredto normal position and said means on the actuating lever is disengagedfrom the supporting abutment, and then about the fulcrum 0n the jet tubeso as to move the throttle to its normal slow idling position. I

3. In a carburetor of the constant suction type having a movablejet'tube and a throttle operating lever, jet tube operating meanscomprising a spring loaded actuating lever fulcrumed on the ment in theform of a fixed stud, a hook-portion on said actuating lever adapted toengage said supporting abutment during a portion of the movement of saidactuating lever, whereb movement of the actuating lever in one directiontakes place first about its fulcrum on the jet tube to eifect partialopening of'the throttle without moving the jet tube, and then about thesecond fulcrum to move the jet tube and the throttle operating leversimultaneously so as to increase the fuel supply and throttle openingproportionately and engage said means on the actuating lever with thesupporting abutment, and subsequent movement of the actuating lever inthe opposite direction takes place first about the second fulcrum so asto move the jet tube and throttle operating lever simultaneously toreduce the throttle opening andfuel supply proportionately until the jettube is restoredtonormal position and said means on the actuating leveris disengaged from the supporting abutment, and then about the fulcrumon the jet tube so as to move the throttle to its normal orslow idlingposition. 7

ERIC G. BAREHAM.

WILLIAM LAYLAND.

References Cited in the file of this patent UNITED STATES PATENTS NumberEricson July 24, 1934 Goldi Nov. 11, 1941 Abell Dec.s23, 1947 MalloryMar. 15, 19 49 Sather June 24, 1919-

